In the so-called drag racing sport for motorcycles, the use of a centrifugal clutch has predominated the art due to its superiority in regulated speed engagement and slip control. Developments to improve this type of clutch are continually being pursued many times based on improvements in existing designs. Dry types of clutches have been employed in the past using materials with a high coefficient of friction for this purpose, however, the motorcycle must be extensively modified making the approach expensive and time consuming.
A search of the prior art did not disclose any patents that read directly on the claims of the instant invention, however, the following U.S. patents were considered related:
______________________________________ Patent No. Inventor Filing Date ______________________________________ 4,732,251 Tipton Mar. 22, 1988 4,566,577 Tsuboi Jan. 28, 1986 4,111,291 Horstman Sep. 5, 1976 1,743,170 Vail Jan. 14, 1930 1,035,535 Coleman Aug. 13, 1912 ______________________________________
U.S. Pat. No. 4,732,251 issued to the present inventor is the art upon which the instant invention is based. The ability to employ existing components from the motorcycle manufacturer and the addition of a basket with a housing gear assembly taught in this prior art patent allows improvements to be made that creates unique multistage control of the function of the slider clutch. Since the inside pressure plate is different and the outside slider plate is replaced and new elements have been added to control function, no anticipation or obviousness with this patent exists.
Tsuboi discloses a clutch release device for motorcycles using a manual actuated hydraulic system in which a push rod is arranged to extend through the main shaft with a pressure plate on each end. One end is arranged to interface with a hydraulic cylinder and the other with the clutch disc pressure plate. It is noted, however, that no centrifugal action is used by this invention and it is assigned to the motorcycle original equipment manufacturer.
Horstman teaches a centrifugal clutch for go-carts and employs weights or stampings that pivot against a plate compressing discs together for engagement, depending upon rotational speed.
Vail uses centrifugal weights forcing separable plates together against adjustable spring pressure, further allowing manually operated means to relieve the pressure on the weights forcing them into an inoperable position allowing shifting of gears.
For background purposes and as indicative of the art to which the invention relates, reference may be made to the remaining cited patents.